ASi-5 Safety

New gateways and first input modules with safe and standard signals are available


ASi-5 Safety is certified and ready for use and complements optimally the established ASi Safety. The latest Safety generation can be easily integrated into existing solutions. Main advantage of ASi-5 Safety: You can use many safe and non-safe signals under just a single address


Discover now our new ASi-5/ASi-3 Gateway family with integrated ASi-5 Safety - as well as the first ASi-5 Safety input modules with 2 safe inputs each and up to 12 standard signals. With them, you can, for example, implement cost-effectively the connection of an operating panel to ASi - with several light buttons, an emergency stop button and a safe key switch.

The advantages of our first ASi-5 Safety modules


ASi-5 Safety is compatible with all previous ASi devices and components and can be easily integrated into existing solutions.

Only one
node number

ASi-5 Safety allows many safe and non-safe signals to be used under just one address.

Complete project can be
saved in the gateway

You even benefit from the modern 16 gigabyte chip card without ASi-5 Safety applications. It can be used to read again all information from the gateway: the safety and hardware configuration, parameter data of connected devices as well as user comments.

Reduced overhead costs
per safe signal

The ASi-5 Safety gateways have the same price level as comparable previous models with ASi-3 safety monitor. Since you can connect many more safe signals per circuit thanks to ASi-5 Safety, the connection costs per safe signal decrease significantly.

input modules

The ASi-5 Safety Modules with 2 safe inputs are comparable in price to our ASi-5 modules that only have standard I/Os. This allows you to significantly reduce machine costs.

The new ASi-5 Safety Gateways

Easy device exchange: If you insert the chip card into a new gateway with the same part number, the complete previous configuration is transferred:


  • Hardware configuration
  • Safety configuration
  • Parameter data of connected devices

The first ASi-5 Safety Input Modules

The ASi-5 Safety Modules with 2 safe inputs are comparable in price with our ASi-5 modules, which only have standard I/Os. This allows you to significantly reduce machine costs.

Fig.: By combining standard and safety signals, many different applications can be achieved from the same module.  

Bihl+Wiedemann has steadily expanded its safety technology solution portfolio since 2005. After a short overview of previous Safety highlights, product manager Paul Werge presents the first two ASi-5 Safety input modules in IP67: BWU4209 has 2 safe inputs for floating contacts, BWU4210 has 2 safe inputs for optoelectronic devices. Both modules additionally have 12 digital self-configuring I/Os each.


Video length: 2:13

FAQs about ASi-5 Safety

There are already many different safety controllers and solutions on the market, but unfortunately the same is also true for the number of functionally safe protocols used and the fieldbus itself.


Fieldbus independence has always been a great strength of ASi and ASi Safety. There are gateways for almost all relevant fieldbuses and safety protocols. This makes the system architecture at the I/O level completely independent of the used controller, which means that it can be standardized across all applications.


Needless to say, this advantage also applies to ASi-5 Safety. Just as with the introduction of ASi-5 in the standard area, ASi-5 Safety also offers many new options. The higher data bandwidth and extended diagnostic and parameterization options are ideal for resource-intensive applications. 

This for example, makes the future implementation of IO-Link Safety possible.

ASi-5 Safety has been an integral part of ASi-5 from the very beginning: both use the same communication technology. In the case of ASi-5 Safety modules, only the normatively required protection of the data is added - with an additional checksum.This makes the transmission of these signals functionally safe up to SIL 3/PLe. This is essential whenever standards require such functional safety to protect people and the environment.

Just like ASi-3 Safety at Work, ASi-5 Safety was once again tested and certified externally according to applicable functional safety standards. Similarly, the process used for ASi-5 Safety achieves a performance level up to PLe according to ISO 13849-1, or a safety integrity level up to SIL3 according to IEC 61508/62061.

Of course, even standard sensors can be connected to ASi-5 Safety modules. With many modules, it is even possible to reconfigure connections so that the signal of the standard sensor is only transmitted via the standard protocol. This especially conserves communication resources such as addresses and bandwidth for ASi-3 Safety modules.

An additional advantage of ASi-5 Safety is that many safe and standard signals can be connected and transmitted over a single address. This saves resources and above all costs.

The topic of cyber security is more relevant than ever. In the industrial sector, the reliability of processes and production in particular is becoming increasingly important.


Like the standard ASi-5 communication, ASi-5 Safety is almost tap-proof due to the nature of the system. The reason:  the data transfer via OFDM with dynamic frequency assignment,makes it very complex to capture the exchanged messages. This requires the entire context of the connection set-up between ASi master and ASi node. Besides, the clock frequencies must be precisely synchronized just like between the ASi master and ASi node according to the ASi-5 protocol.


Cyber security is also enhanced by the fact that the gateway creates a logical break between TCP/IP, ASi-5, and ASi-5 Safety. This means that high safety requirements only need to be placed on the ASi-5 Master, which establishes the connection to TCP/IP. ASi-5 modules, on the other hand, are much less problematic in terms of safety, since they cannot communicate over TCP/IP networks. Those responsible for network security can thus focus on significantly fewer devices and check them more carefully.

Like ASi, ASi-5 Safety is characterized by maximum stability and availability. Defective masters can therefore be replaced easily and without complications: Thanks to the backup in the ASi master, the replacement device is automatically addressed and parameterized just like the original device .

ASi-5 Safety is very flexible: depending on the profile and application scenario, 1 to 64 safe process data along with additional standard  – each bidirectional – can be exchanged with one module. In the process, cycle times of up to 1.27 ms can be achieved for up to 16 safe inputs and 16 safe outputs each. Available diagnostics and acyclic services have no influence on the cycle times.

As an integral part of ASi-5, ASi-5 Safety can transmit safe and standard data simultaneously. Up to 32 bytes are available cyclically for this purpose. The safe data always has a 1-byte checksum, which enables safe communication up to level SIL3/PLe. As with pure ASi-5 standard modules, there is also a diagnostic and an acyclic channel. This also allows ASi-5 Safety modules to transmit detailed diagnostic messages in case of an event. An additional high-performance method is also available to read out additional information if required – e.g., for predictive maintenance or similar applications.

ASi-5 Safety uses the same mechanisms as all other ASi-5 modules. This means that it provides cyclic data along with an event-based diagnostic channel and an acyclic channel for reading out numerous indices. These indices cover a wide range of information: manufacturer, model name, the ASi ID for unique identification, module temperature, measured currents or an hour meter, to name a few." OPC UA enables this information to be transmitted to IT for evaluation..

This can save considerable costs in applications with multiple signals. ASi-3 Safety can also be used for modules that have many signals. In this case, however, each safe signal occupies a separate address. Just as with ASi-5, ASi-5 Safety can process much more data per master and thus greatly reduce connection costs – thanks to the significantly higher data bandwidth per address. For example, with the ASi-5 Safety module BWU4210, a total of 2x2-channel safe inputs and an additional 12 I/Os are available under just one ASi-5 address. In contrast, the same amount of data occupies 2 single and 3 A/B addresses with ASi-3.

However, ASi-5 may not always be the most advantageous one. Even with ASi-3 Safety, only one address is occupied for a single E-stop with a 2-channel safe input – and at lower cost. Both technologies will therefore be used in parallel in the future.

ASi-5 and ASi-3 operate independently and in parallel on the same two-conductor cable with the same electromechanics. Only one gateway with a combined ASi-5/ASi-3 master is required when using both protocols in one installation. The same applies to ASi-5 Safety and ASi-3 Safety – all that is needed is a gateway with a combined master and a combined ASi-5/ASi-3 safety monitor. In the simplest case, it is therefore possible to just replace the gateway in an existing system with ASi-3 Safety. The system can then continue to operate without changes, and ASi-5 Safety modules can be easily added if necessary.

ASi – A resource-saving technology

Thanks to the greatly reduced wiring effort with AS-Interface, you save assembly and material costs. This saves valuable resources.


More information!